Treatment of refractory metals.



e, GM U R-ZEHNDER.

TREATMENT OF REFRACTORY METALS.

APPLICATION FILED JAN. 5. 1915.

2 SHEETS SHEET 1.

1,150,670. Patented Aug. 17', 1915.

g z Q G. GMUR-ZEHNDER.

TREATMENT OF REFRACTORY METALS.

APPLICATION FILED JAN. 15, 1915.

Patented Aug. 17, 1915.

2 SHEETS-SHEET 2.

I I r? UNITED STATES. PATENT FFICE.

GOTTLI'EB GMtl'R-ZEHNDER, OF AARAU, SWITZERLAND.

TREATMENT OF REFRACTORY METALS.

Application filed January 15, 1915.

To all whom it may concern:

Be it known that I, GOTTLIEB GMiiR-Znnraman, a citizen of the SwissRepublic, residing at Aarau, in the Republic of Switzerland, haveinvented certain new and useful Improvements in Treatment of RefractoryMetals, of wh ch the following is a specification.

This invention relates to the treatment of refractory metals andprovides an improved process and apparatus especially but notexclusively intended for the manufacture of I metallic tungstenin a formsuitable for the formation of metallic lamp filaments.

The process is based upon my discovery that if tungsten isfused to 'aperfectly liquid condition and is then very rapidly cooled it will notform a coarse crystalline grain (as is the case with a tungsten alloycontaining even a minute proportion of other metals) but will beexceedingly fine in its granular structure and will be perfectlymalleable and ductile.

My process, therefore, consists in fusing tungsten (usually in the formof a powder obtained from the oxid by any of the well known processes)in an electric furnace into a perfectly liquid state and in thensuddenlycooling the liquid mass. The fusion and subsequent rapid coolingare preferably effected in an electric furnace of resistance type, inwhich the tungsten is placed in an inner receptacle heated byradiatidnfrom 'the inclosing walls of the resistance material I (about 3000 C.)the cold air blast is the most efficient means of rapid cooling,ordinary methods of cooling by liquids being unsuitable owing to theinstant formation of badly conducting layers of vapor.

I An electric furnace embodying my invention is shown in theaccompanying drawings, in which Figures 1 and 2 show a typical furnaceSpecification of Letters Iatent.

Patented Aug. 1'7, 1915.

Serial No. 2,478.

with electrical and mechanical connections in diagrammatic form, thefurnace being illustrated in closed and open positions.

a is a tube of graphite or hard carbon or other suitable refractorymaterial, which receives the substance (1. that it is desired to fuse.

b is the inner heating tube and c the outer inclosing tube, both ofgraphite or other highly refractory material possessingthe necessaryconductivity.

d and e are respectively the top and bottom blocks which close both endsof the tubes 6 and 0 when the furnace is closed, the tubes being, in theconstruction illustrated, carried by the upper block d which can beraised or lowered to open or close the furnace.

The tubes 6 and c and blocks d and 6 may all be of the same material.

When the furnace is closed current is supplied through the leads g, gand top and bottom blocks 0Z and e to the two tubes 6 and a, which areheated by the current to any temperature desired. Since the temperatureof the inner surface of the outer tube 0 is substantially the same asthat of the tube 72 loss of heat by radiation from the latter is almosteliminated, external losses being practically confined to radiation fromthe outer surface of the outer tube. The outer tube also combines withany oxygen which may enter or remain in the furnace and protects thesubstance at from oxida tion/ The central tube a and its contents aresoon raised by the internal radiation of heat from the inner walls ofthe tube 5 to practically the same temperature as that of the tube and acomplete and homogeneous fusing of the highly refractory metals or theblock 0? with the tubes 6 and c is raised into theposition shown in Fig.2 by means of the rope orcord it connected to the lifting arms f andpassing over pulleys to a counter-weight. The operation may be effectedby the lever i forming a contact breaker or switch at 70 so that theelectrical circuit is broken at this point immediately the furnacebegins to open.

For rapid cooling of the substance in the central tube a a blast coldcompressed air is provided through the elongated fun- Z ide the ertcrnal casing m and directed upon the tube a from both sides. The

air supply is preferably turned on automatically on opening the furnaceso that the cooling action maybe made extremely rapid.

In starting the operation the tube a is filled with the material (Landinserted While thefurnace is open as in Fig. 2. On lowering'the block (Zand tubes 6 and 0, when the latter meet the lower block 6, the circuitis automatically completed and the current passes through the tubes 2')and 0 until the contents of the furnace are fused or brought into thedesired condition.

What I claim and desire to secure by Letters Patent of the United Statesis 1. A process for producing pure malleableand ductile tungsten,consisting in fusing the metal to a perfectly fluid state and thenrapidly cooling the same.

2. A process for producing pure malleable and ductile tungsten,consisting in fusing the metal to a perfectly fluid state and thenrapidly cooling the same by a blast of cold air.

3. A process for producing pure malleable and ductile tungsten,consisting in fusing the metal to a perfectly fluid state by radiantheat produced electrically, and then rapidly cooling the metal.

4. A process for producing pure malleable and ductile tungsten,consisting in fusing the metal to a perfectly fluid state by radiantheat produced electrically, and then rapidly cooling the metal by ablast of cold air.

5. An electric resistance furnace for refractory materials, comprisingan inner chamber formed by Walls of conducting material inclosingfthesubstance under treatment and a surrounding chamber whose walls areseparated from the inner chamber by an air space and also carry currentand are heated to about the same temperature as the walls of the innerchamber. A

6. In an electric resistance furnace for refractory materials, twoconcentric vertical current conducting tubes inclosing the materialunder treatment, top and bottom conducting blocks between which thetubes are mounted and means for raising the tubes to open the furnaceand break the electric circuit through the tubes.

7. In an electric resistance furnace for refractory materials, an innerand an outer vertical heating tube, both tubes carrying current, top andbottom conducting pieces between which the tubes make contact, and

an inner vesselcontaining the material under treatment and preventing ittaking any ing walls, means for opening the furnace and exposing thecontents and means for supplying a blast of cooling air on opening thefurnace.

' 9. In an electric resistance furnace for refractory materials, Lwoconcentric vertical current conducting, tubes inclosing the materialunder treatment, top and bottom conducting blocks between which thetubes are mounted, means for raising the tubes to open the furnace andbreak the electric cir cuit through the tubes, and means for supplying ablast of cooling air to the heated material on raising the tubes.

10. In an electric resistance furnace for refractory materials, twoconcentric vertical current conducting tubes inclosing the materialunder treatment, top and bottom conducting blocks between which thetubes are mounted, means for raising the tubes to open the furnace andbreak the electric circuit through the tubes, and air blast funnelsdirected upon the heated material.

11. In an electric resistance furnace for refractory materials, twoconcentric vertical current conducting tubes inclosing the materialunder treatment, a bottom conducting block on which the tubes rest, anupper con ducting block 'to which the said tubes are fixed and means forraising the upper block and the tubes to open the furnace.

12. In an electric resistance furnace for refractory materials, twoconcentric Vertical current conducting tubes inclosing the materialunder treatment, a bottom conducting block on which the tubes rest, anupper conducting block to which the said tubes are fixed. means forraising the upper block and the tubes to open the furnace, an externalcasing receiving the furnace and a plurality of air blast funnels insidethe said casing and directed toward the center of the furnace.

In testimony whereof I ailix my signature in presence of two witnesses.

GOTTLIEB GMUR-ZEHNDER.

Witnesses HY. WIEFLISBACH, Snzcrn. ANGST.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patent: Washington, D. 0."

